arrMongoDatabases={
    "blog":["php","test"],
    "study":["java","mongo"]
}


var arrMongodb = JSON.stringify(arrMongoDatabases);

var arr= JSON.parse(arrMongodb);
for(db in arr){
    console.log(db)
    var coll = arr[db];//get collections as a array
    for(var i=0;i < coll.length;i++){
        console.log(coll[i]);//get any single item
    }
    console.log("-----------")
}

console.log(arr.blog[0]); // get "php"
console.log(arr.study);//["java","mongo"]
